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ABSTRACT: At present, the temperature-resistant steels with a rapid reduction of induced radioactivity appear to be a perspective structural
material for new-generation nuclear and thermonuclear reactors. Special attention is paid to the nanostructural state of the
elaborated materials. In this work, for the first time, there have been carried out tomographic atom-probe studies of the
chromium ferritic-martensitic steel EK-181 (RUSFER EK-181) with 12% Cr. Spatial distributions of chemical elements in the
investigated volumes of the material with an atomic resolution have been obtained. The dimensions of the investigated portions
of the material are on the order of 10 × 10 × 30 nm3. There have been observed nanosized preprecipitates (nanoclusters), i.e., regions enriched in V, Cr, and N atoms, with characteristic
sizes of about 3 nm.
The Physics of Metals and Metallography 05/2012; 108(6):579-585. · 0.54 Impact Factor
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ABSTRACT: Oxide dispersion strengthened steels possess better high-temperature creep and radiation resistance than conventionally produced ferritic/martensitic steels. This behaviour is mainly caused by the presence of highly dispersed and extremely stable oxide particles with diameters of a few nanometers. In this work the nanostructure of ODS Eurofer steel was investigated by means of tomographic atom probe and correlations with recent TEM and SANS studies were derived. The present investigation revealed nanoscaled clusters of typically 2 nm diameter containing not only yttrium and oxygen but also vanadium and nitrogen. Moreover, concentration of vanadium in particles was found to be higher than that of yttrium, which indicates the importance of these elements in cluster formation. The estimated average cluster number density is about 2 x 10(24) m(-3). These enriched zones might be evidently attributed to precursors of the larger precipitates observed by TEM. This conclusion is also supported by the similarities of the chemical composition inside enriched zones seen in both atomic probe and TEM data. (C) 2010 Elsevier B.V. All rights reserved.
Journal of Nuclear Materials. 409(2):65-71.
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ABSTRACT: Our previous investigations of unirradiated ODS Eurofer by tomographic atom probe (TAP) revealed numerous nano-scaled features (nanoclusters) enriched in vanadium, yttrium and oxygen. In this work the effect of neutron irradiation on nanostructure behaviour of ODS Eurofer (9%-CrWVTa) was investigated. The irradiation was performed in the research reactor BOR-60 (Dimitrovgrad, Russia) where materials were irradiated at 330 degrees C to 32 dpa. TAP studies were performed on the needles prepared from parts of broken Charpy specimens. For all specimens except one, which was tested at 500 degrees C, the Charpy tests were performed at temperatures not exceeding the irradiation temperature. A high number density 2-4 x 10(24) m(-3) of ultra fine 1-3 nm diameter nanoclusters enriched in yttrium, oxygen, manganese and chromium was observed in the irradiated state. The composition of detected clusters differs from that for unirradiated ODS Eurofer. It was observed in this work that after neutron irradiation vanadium atoms had left the clusters, moving from the core into solid solution. The concentrations of yttrium and oxygen in the matrix, as it was detected, increase several times under irradiation. In the samples tested at 500 degrees C both the number density of clusters and the yttrium concentration in the matrix decrease by a factor of two. (C) 2010 Elsevier B.V. All rights reserved.
Journal of Nuclear Materials. 409(2):94-99.
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ABSTRACT: Atom probe tomography has been used to investigate nanoscale features in the yttrium oxide dispersion strengthened steel ODS Eurofer, which is a perspective structural material for the reactor cores. In the initial material, a large number (similar to 2 x 10(24) m(-3)) of ultrafine (similar to 2.5 nm in diameter) clusters enriched in yttrium, oxygen, nitrogen, and vanadium have been revealed. The investigation of the ODS Eurofer steel irradiated at 330A degrees C to 32 dpa in the BOR-60 fast reactor has also revealed a large number of ultrafine (1-3 nm in diameter) nanoclusters significantly enriched in yttrium, oxygen, manganese, and chromium. In the irradiated material, an increase in the concentration of clusters and changes in the chemical composition of the clusters and matrix have been noted. The irradiation by fast neutrons leads to a partial transition of vanadium from the clusters into the surrounding matrix and to a general increase in the concentrations of yttrium and oxygen in the volumes under investigation.
The Physics of Metals and Metallography 113(1):98-105. · 0.54 Impact Factor
